Australian authorities appear to have ignored requests by Julian Assange for diplomatic assistance, including a letter sent as recently as 15 days ago, his lawyer said this morning.

Judge Baltasar Garzón Real also revealed key information relating to the rape allegations facing Mr Assange had been kept secret and would be a "big surprise" when the defence team was able to reveal them.

The Spanish lawyer, who was addressing an archivist conference in Brisbane today, spent four hours in a briefing with Mr Assange on Sunday discussing his legal strategy.

The veteran international lawyer, who ran a case against Chilean dictator Augusto Pinochet, was critical of Australian authorities for failing to provide consular assistance to Mr Assange.

Mr Garzón said the Australian Government's response to requests for assistance had been "entirely negative".

"A letter has been sent on the part of the defence [of Mr Assange] to diplomatic authorities and the Department of Foreign Affairs of Australia requesting a number of guarantees as well as information," he said through an interpreter.

"The response has been entirely negative for each and every one of the requests and some 15 days ago we have channelled another communication and request to the Australian authorities and for the time being we have not received a response.

"Not at any point in time have consular authorities visited Mr Assange.

"And I understand that to be an obligation for all citizens of Australia men and women of Australia who happen to find themselves in a similar situation have the right to consular assistance and they should not be in a position of having to request it."

Mr Garzón refused to divulge the contents of the letter sent to Australian authorities 15 days earlier.

"It's a letter in which a number of issues are being raised in relation to Mr Assange's situation and on the procedure itself,'' he said.

But he suggested it related to Mr Assange's rights as an Australian citizen not being recognised.

"Although Mr Assange has had his passport withheld and he is a refugee at the Ecuadorian embassy, he is indeed a citizen of Australia and has therefore all his rights, although however seemingly they aren't being adhered too,'' Mr Garzón said.

When asked about the specific rape allegations facing his client, Mr Garzón declined to go into specifics but said there was "fragmented knowledge" about the matter.

He said the defence was in possession of a number of fundamental elements about the rape allegations, that when made public, would be surprising.

"We cannot divulge them right now but we have requested that the prosecution take a statement from Mr Assange,'' he said.

Mr Garzón speculated the reluctance of Australian authorities to help his client was because "relations are not good with Mr Assange quite likely given the entire WikiLeaks affair".

Mr Garzón said the defence had requested the possibility for a prosecutor from Sweden to travel to London to take a statement from Mr Assange.

"I think that will be a very good option and later on of course we will be willing to listen to the other requirements," he said.

Mr Garzón said Mr Assange was in perfect health, but the living conditions in the embassy were not ideal.

"The treatment is good but a prolonged situation such as that where he has limited space with practically no access to natural light does limit the physical well being of the person and can be deemed a rather concerning humanitarian situation," he said.

Comment has been sought from DFAT.

Mr Assange, the 41-year-old founder of WikiLeaks, has been facing extradition to Sweden over rape allegations.

The allegations relate to rape, sexual molestation and unlawful coercion made by two Swedish women known as woman A and Woman B, whom Mr Assange met in Stockholm in August 2010.

Mr Assange, a former computer programer, has been granted political asylum by Ecuador on the grounds that he feared persecution and the possible death penalty in the United States in connection with leaked top secret government information published by WikiLeaks.

He sought asylum after the British Supreme Court rejected his last appeal in June. He has been living in the Ecaudorian embassy in London ever since.